Grinding machine



April 3 9- L.RUPRECHTETAL 1,711,464

GRINDING MACHINE Filed Feb. 10, 1927 2 sheets-sheet 1 H 4 INVENTOR P m 3Win. g flan/d. H J W-QM" aka-ATTORNEY April 2 L. RUPRECHT ET AL GRINDINGMACHINE 2 Sheets-Sheet 2 Filed Feb 7 10,; 1927 444.4 ATTORNEY mm mm, ornom'cmm,

Patented Apr. 30, 1.929.?

UNITE]? STATES eamnme mourns.

Application fled ass 10,1927. Serial at. 167,169.:

This invention relates to a machine for performing grinding or likecomminuting operations, and adapted to the requirements of" variousindustries, such as color grinding and numerous other purposes,particularly where uniformity in the size of the ground articles is adesider'atum.

The invention relates particularly to the type of. grinding machine inwhich the material'to be ground is fed by means of a feed screw or-wormto a rapidly rotated and'en 7 also results infiner and moreuniformgrinding than could otherwise be obtained. A further object of theinvention is to present the material uniformly. along the length of therinder. This conduces to uniform grin mg, and also permits the use ofgrind-- ers of" any desired lengthr The means by which these and otherobjects of the invention are attained may best be understood from adetailed description of an illustrative f swing hammergrindingmachine'embodying the invention which is shown in the accompanyingdrawing, in which Fig. 1 is'a-planview of the machine with the cover ofthe main casing and 'the feed hopper removed; I v y a Fig. 2 isatransversesectional view taken on the-line 2-2 of Fig. .1;

Fig. 3 is a longitudinal; sectional viiew taken on the line 33 of Fig. 1

Fig. 4 is a fragmentary transverse section on the line 4-4 of Fig. 1;and Fig. 5 is a detail view. The machine illustrated includes a maincasing 10 within which is a rotary grinder 11, a eed conduit 12extending from the main casing, feed screws 13, 13, 13 in thefeedconduit, and a' feed hop er114 opening into} the top of the feed con uitat a-substantial.

distance from the main casing. The grinder 11-is of known'form, andconsists of a plurality of alternately turned hubs 15to whlch arepivoted hammers. or boaters 16. The hubs 15 are as'sembledon the middlepart of a mainshaft 17 which extends across the casin 10, and isprovided with bearings 18 carrie by theside walls 19 of the casing.

While the main casing may be made recend edges of the screen are en ageda tangular as showmit encloses a cylindrical; gr ndmg chamber 20providedby a cylin-fi drically curved cover 21 enclosin the to of thegrinder and a cylindrical y curv screen 22 located within the casingclosing'the' lower half of the grinder. I z

23*, are fixed on'the main. sha

t 17 at opposite e5 sides of the inder ll-and close to the inner f v 1surface of t eside walls of the casing. 'Although these disks are shownas flat, th -m be flanged orcurved or otherwise "deformed.

if desired, and for this reason the word disk I as used herein is not tobe'u'nderstood to be limited to a flat disk. The disks 23, 23 containcentral openings which fit tightly on the i shaft, so that no dust canpass between them and the shaft. The rapid rotation of the shaft, whichis necessary for'efiective o eratlon of the grinder, causes these di 5to throw radially outward any dust-or grit which may move along theshaft or alon the central part of the casing towards the ear-.

.ings 18. Such dust is thus prevented from a entering the bearings.Furthermore, al-

though the disks are notin actual contact; with the side walls of thecasing, they are;

located so near these side walls that any dustr fili or grit whichattempts to enter between them I an the casing is mmediately thrown outradiall Consequently no dust or ritcan nter t e bearings. 18. This is ana vantage 4 of great practical importance, since when previous grindingmachines of the samegenera-l character have been applied to grin in'ggritty materials, it has been found' necessary to .replacethe shaftbearings at frequent m-. tervas. I I A feature of the invention consistsin providing insane for facilitating the removal and replacement of thescreen 22. This s impor-f tantsince the mesh of this screen shouldcorrespond to the fineness of the grindin re 100 quired.-' The sideedges of this scream-w ich may be of the 'usual form of a thm screenplate mounted on a skeleton back late or of othersuitable form, are heldin c annels 24 W! 2 provided in the inner surfaces of thes1de walls 19of the main casing, as by ribs 25. cast or otherwise formed thereon. Theupper or by removableshold-down bloc s .26, 27.- The ends' of theblock2.6 have'a 'slidable'engage- 1i0 and em." no; i

lpreventing thepulverized material or I dust w ich is formed in thegrinding chamber I. 20 from entering the bearings 18, disks 285-.

held

ment with vertical grooves 28 formed in the side walls of the casing.This block is normally held down against one end edge of the screen bythe cover 21, but may be lifted out vertically to permit removal-of thescreen when this cover is removed. The block 27 contains a centralopening which forms the inner end of the feed conduit 12 in which thescrews 13, 13", 13 are located, so that, this block cannot be raisedvertically like the block 26. The grooves 28 in the side walls 19 inwhich the ends of this block are held are, therefore, made wider thanthe block, so that the block ma be moved horizontally inward to uncoverthe upper" end of the screen 22,

and thus to permit the application of a pressing instrument to this edgeof the screen to force the screen out'at the opposite end of the casing.If rigidly supported hammers are used, this will, of course, be donewhen the grinder is so turned that none of the hammers are directlyopposite the block 27. To retain the block 27 in its normal operativeposition and out of the path of: the heaters during the operation of themachine, filler pieces 29 are inserted in the grooves 28. These piecesare held in position by the cover 21. It is apparent that thearrangement described. provides for ready removal and replacement of thescreen, and at the same time holds the screen rigidly in its properposition during the operation of the machine. In order to prevent anypossible protrusion of any part of the end edges of the screen into thepath of the ends of. the hammers, or direct wearing contact of therapidly moving material in the chamber with the end edges of the screen,the blocks 26 and 27 are provided at their lower inner edges withdownwardly projecting flanges 26" and 27*, most desirably tapered asshown, which when the parts are positioned extend in front of the screenedges.

Important features of the invention are embodied in the means forfeeding the material to be ground into the grinding chamber 20.-

The feed opening 30 into this chamber from the conduit 12 is provided bythe opening in the hold-down block 27 It is narrow but of sufiicientlength to extend a substantial distance along the axial length of thegrinder 11. When the feed conduit is arranged to feed the material in ahorizontal direct-ion as shown, the feed opening 30 is locatedsubstantially on the level with the axis of the grinder, although it isdesirable to place the middle of the opening slightly above this axis sothat the lower edge of the opening is on the level with the axis. 7

'The feed ponduit 12 extends to the feed opening 30 and is mostdesirably of the same width andheight as the feed opening. In order thatthe,feed screws'13, 13 and 13 may deliver the material to the grinder ina compacted mass, the feed conduit extendsin such wardfinclination. Formost materials, itlnost desirably extends horizontally, as shown.

The inner portion of the conduit is closed,

while'the top of the outer portion of the conduit is in communicationthrough a supply opening 31 with the feed hopper 11in The floor of theconduit 12 is formed to provide a plurality of semi-circular grooves 32,32, 32 extending lengthwise of the conduit. A plurality of feed screws13 13", 1o, corresponding in number tothatof these grooves, are locatedin the feed conduit coaxially with the grooves, and in such manner thattheir threads just clear the grooves. The upper wall 33 of the enclosedinner portion of the conduit is formed to provide correspondingsemi-cylindrical grooves 34*, 34, 34 which closely enclose the upperportions of the threads of the screws.

The feed. screws are supported entirely from their rear ends. Each screwextends from a shaft 35 which is provided with spaced bearings 36located beyond the outer end of the feed conduit. Each screw is mostdesirably'made integral with its supporting shaft. This mounting of'thefeed screws not only avoids the use of a bearing in the feed conduit,which would tend to obstruct the movement of the material. but also hasthe advantage of making it possible to extend the feed screws to apointvery close to the periphcry of the grinder. This results in finer andmore efficient grinding than would otherwise be obtainable.

In order to supply the material uniformly across the length of thegrinder, all the feed screws are most desirably rotated at the samespeed by a common driving means which, in

the form shown, consists of a worm 38 engaging' gears 39 of uniform sizefixed on the shafts of the screws In order to provide for a constantratio between the speed of the grinder and that of the feed screwsduring an operation of the machine, the worm 38 is connected with themain shaft 17, for example. by means of a belt 40 and appropriate beltpulleys, as shown.

In the operation of the machine which has been described, the materialto be ground is placed in the hopper 14 in such manner that it feedopening, successively strike the end of the compacted mass of materialfrom below as it is-forced into the grinding chamber, and act tocomminute it. As the material becomes sufliciently connninuted, itpasses through the screen 22, and may be collected in a bag ell or othersuitable receptacle at the bottom of the main casing 10. As will beunderstood by those skilled in the art, the fineness ot'the grinding maybe regulated by changing the screen and hychanging the speed of thegrinder and the feed screws, and to some extent by changing the ratiobetween these speeds. The higher the speed of the grinder and the finerthe screen, the finer the grinding. While the speeds at which the highspeed grinder and the relatively low speed feed screws should be drivendepend on the nature of the material being ground and the fineness ofgrinding required. it may be noted by wayof illustration that the speedof the grinder v has been varied from 500 to 5500 R. P. M., and that ofthe feed screws from to 200 R. P. M., depending, as stated, on thefineness of grinding-required, the kind of material being ground, andalso on the size of the grinder and the size and pitch of the feedscrews. v

What is claimed is:

1. A machine of the class described, comprising a main casing, a feedconduit extending to an opening in the periphery of the main casing atan angle such that gravity does not urge the materialin the conduittoward the main casing and provided with a supply opening at asubstantial distance from its inner end, a feed screw in said conduitadapted to move material along the conduit and to force it into the-maincasing in a compacted mass, a plurality of heaters in the main casing,and means for moving said heaters so thatthey successively strike frombelow the compacted massforced' into the casing by the feed screw. Amachme of the class descrlbed, com-. prising a horlzontal cvlindrlcalmain casing,

a feed conduit extending horizontally to an opening in the periphery ofthe main casing opening into themain casing, a grinder in the maincasing, beaterson said grinder, and

of, the teed screw.

' means for rotating the grinder so that'theheaters move upwardly acrossthe inner end ,3. A' machine of the class described, comprising arotary'grinder, a main casing enclosing a cylindrical chamber having aperipheraladmission slot extending parallel to said opening 'extendingtosaid opening and I provided with a supply opening in its top 10-conduit, spaced bearings for said shaft 10-.

cated a substantial distance from its inner end, and means in the feedcondult for compacting the material to be ground and forcing y itthrough said slot at a uniform rate along the length of the slot. v

4. A machine of the class described, comprising a main casing enclosinga cylindrical.

chamherhaving .an oblong peripheral opening extending parallel to itsaxis and substantially from one of its ends to the other, a rotarygrinder in the casing, a feed conduit whose cross-section cor-respondsto said opening extending to said opening and provided with a supplyopening inits top located a substantial distance from its inner end, aplurality of feed screws located side by side in the feed conduit, andmeans for rotating all of said feed screws at the same rate.

5. A machine of the class described, comprising a main casing, a, rotarygrinder there- 1n, afeed conduit extending to an opening 1n theperiphery of the casing and having a supply opening at a substantialdistance from its inner end, a shaft at the outer end ofsaid catedbeyondsaid opening, and a feed screw located in the conduit with itsinner end close to the periphery of the grinder and wholly supported bysaid shaft.

.6. In a machine of the class described, the combination of a wide,shallow, horizontal feed conduit having a plurality of longitudinal,semi-cylindrical grooves in its-bottom, a plurality of feed screws insaid conduit each of which is coaxial with one of said semicylindricalgrooves, and driving'rneans for said feed screws positively connectedto. each of them. b

7 In a machine of the class described, the combination with a maincasing, a rotary grinder therein, a feed conduit opening to' the maincasing, and a feed screw in'the con-' of the grinder andsubstantiallyonthe level with its axis, of a screen support below the grinder, acylindrically curved screen supported thereby, a removable blockengaging the upper edge of the screen at the side of thegrinder oppositeto the feed screw, and a re- 1' movable block which engages the otherupper edge of the screen, contains an opening for the passage of thefeed screw, and is'monnted' so as to slide longitudinally of the feedscrew to expose said upper edge of the screen.

8. A 'pulverizing machine, comprising means for horlzontally compactingmaterial to be pulverized, and moving it horizontally,

and heaters successively striking the forward In testimony whereof, wehave hereunto set our hands.

LOUIS RUPRECI-IT.

portion of the compacted mass from below. the axis of the grander andsubstantially from Y ALFRED G. KoLLs'rnnEI

